With the promotion and popularization of digital imaging technology, optical imaging devices are widely used in a variety of equipments, such as a wide variety of portable and small equipments. Needs for miniaturized optical imaging devices widely exist.
In order to make the imaging devices to have the ability of precisely adjusting the focus in the case of miniaturization, solutions in which a thread-driven ultrasonic motor is used to adjust the focus (for example, referring to the PCT application publication No. WO2007118418) and zoom (for example, referring to the Chinese application publication No. CN102590979A) have been proposed. These technologies can be used to miniaturize the zoom lens assembly. However, there is no feasible solution for telescopic miniaturized zoom lens assembly yet.
Currently, there are, in general, several kinds of telescopic lens as following:
a large lens assembly (such as the lens assembly of a SLR camera) which generally has larger front end caliber and smaller rear end (the end connecting with the camera) caliber, and in which a manual zooming is used to telescope the lens assembly and zoom; and
a telescopic lens assembly with the ability of automatic (powered) zooming, which generally has a structure of multi-sleeves and in which the telescoping is performed by the inner sleeve. However, since the inner sleeve has smaller caliber, it is difficult for the telescopic lens assembly to have wide-angle effect. If a wide-angle lens assembly is needed, the multi-sleeves will be stubby, which leads to that the zoom factor will be greatly limited and the dimensions of the rear end of the lens assembly will be further increased.
Both of the two lens assemblies mentioned above are difficult to be miniaturized.